SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90a5b1fa6ed4110d785d8dddae71a40682650b0de5b2161d7c16df5e59a3b248' 
  AND token = 'Dlz09C6WaJCZMmKShzT+r9EfrA/5aeu2G2YJpMo+RyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}